Style simple with 1-3 stigmas or 2-parted. Herbs or undershrubs. 738 738. Stamens 5. Corolla with valvate aestivation. =219. Rubiaceae.= Stamens 1-4. Corolla with imbricate aestivation. 739 739. Flowers in heads. Calyx surrounded by an epicalyx. Stamens 2-4. Seed albuminous. =222. Dipsacaceae.= Flowers in cymose inflorescences, without an epicalyx. Stamens 1-3. Seed exalbuminous. =221. Valerianaceae.= 740. (731.) Ovules basal or apical or inserted upon a free central placenta. 741 Ovules inserted upon two or more parietal placentas. 745 741. Calyx of 2, corolla of 4-6 divisions. Stamens as many as and opposite the divisions of the corolla or more. Herbs or undershrubs. _Portulaca_, =73. Portulacaceae=. Calyx and corolla of 4-5 divisions each. Stamens as many or fewer. 742 742. Ovules basal or apical. Stamens as many as and alternate with the divisions of the corolla or fewer. Corolla usually with valvate aestivation. 743 Ovules inserted upon a free central placenta. Stamens as many as and opposite the divisions of the corolla. Corolla with imbricate aestivation. 744 743. Flowers hermaphrodite. Stamens free. Ovules 4, basal. Stigma 2-lobed. Seeds albuminous. Undershrubs. _Merciera_, =224. Campanulaceae=. Flowers unisexual or polygamous. Seeds exalbuminous. =223. Cucurbitaceae.= 744. Staminodes alternating with the fertile stamens. Fruit a capsule. Herbs or undershrubs. _Samolus_, =191. Primulaceae=. Staminodes wanting. Fruit a berry or nut. Shrubs. _Maesa_, =190. Myrsinaceae=. 745. Stamens numerous. Flowers hermaphrodite. Fruit a berry. Seeds albuminous. Succulent, usually leafless plants. =167. Cactaceae.= Stamens 2-11. Leafy plants. 746 746. Corolla with contorted aestivation. Stamens 5-11. Fruit capsular. Seeds albuminous. Leaves opposite or whorled, undivided, stipulate. =219. Rubiaceae.= Corolla with valvate, rarely with imbricate aestivation. Stamens 2-5. Flowers unisexual or polygamous. Fruit berry-or nut-like. Seeds exalbuminous. Leaves nearly always alternate. =223. Cucurbitaceae.= 747. (729.) Ovaries 2, distinct. Styles more or less united above, stigmatose beneath the thickened apex. Stamens 5. Leaves usually opposite. 748 Ovary 1. 749 748. Stylar head with 5 gland-like pollen-carriers alternating with the anthers, to which the pollen united into masses adheres. Styles free below the thickened apex. Disc wanting. =201. Asclepiadaceae.= Stylar head without pollen-carriers, but sometimes adhering to the anthers. Pollen of free grains. =200. Apocynaceae.= 749. Ovules solitary in each ovary-cell. 750 Ovules 2 or more in each ovary-cell. 758 750. Leaves opposite, whorled, or all radical. 751 Leaves alternate. 753 751. Stamens fewer than the divisions of the corolla, 1-3. Ovary 3-celled. Seeds exalbuminous. Herbs or undershrubs. =221. Valerianaceae.= Stamens as many as the divisions of the corolla. 752